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Friday, Sept. 28, 2001
By ROWAN HOOPER
* Japanese name:Ruritateha * Scientific name:Kaniska canace * Description: This is a large, striking butterfly. Both sexes are similarly colored, with dark wings and body, and a couple of white spots and distinctive blue stripes on the wings. The color and the markings are so eye-catching that the butterfly can be identified on the wing. Part of the Japanese name, "ruri," means deep blue. Adults have a 6-cm wingspan; the forelegs are poorly developed. Blue admiral caterpillars are equally striking -- they have black and orange bodies, and are covered in spiky hairs, sprouting mushroomlike in tufts all over the body. * Where to find them: From the lowlands to the mountainsides all over Japan, though they are less common in Hokkaido. The species is found from Central to East Asia; they are strong fliers and can migrate long distances. Adults fly from March, eggs are laid in early autumn, and the caterpillar lives mainly on the underside of plant leaves (hiding from predators such as birds), where it grows from 3 mm to 4 cm long. The larval stage lasts about 23 days. After that, the caterpillar pupates. The pupal case is about 3.5 cm long and is attached by silk to a twig. After about 12 days, the adult butterfly will emerge. * Food: Caterpillars eat plant leaves -- they especially like sweet potato. Adults feed on fermented juices from rotten fruit and tree sap. * Special features: The iridescent wings of the blue admiral, and of most butterflies, are not colorful because of bright pigments in the wings, but because of the structure of the scales on the wings. These refract, or bend, light so as to reflect different colors. In contrast, the underside of the wings are cryptically colored, so that the butterfly is hard for predators to spot. Caterpillars have orange warning colors, but if a bird is daft enough to try and eat it, the tufts on the caterpillar's body will catch in its throat and the bird will learn to avoid similarly colored caterpillars in the future.